I have been using Laptops for gaming for near on 6 years now and no real issues at all. The only downside is the obvious small screen (but doesn't mean you can't plug a nice monitor in when at home! I run a 27" Samsung LED, the joys of HDMI) & limited upgrade options for obvious reasons.
Personally I stick by Toshiba, however am very impressed with what Dell are doing these days. You can usually find a very impressive lappy from them for relatively cheap on their online store.
I have a close friend who has advised me to steer clear of HP because of poor manufacturing, don't know if it's true or not but he knows his stuff.
Also if it's any help, I run SC2 on medium settings at about 30 - 50fps on my old Toshi and she's going on 2 years old. (2.13Ghz Centrino Dualcore, 4Gb RAM, RadeonHD3650 etc.)
Lastly yet perhaps not so relative due to you sharing your preferred budget, if you were after a "beast" in terms of Laptops/Gaming then I'd check out Alienware or again Dells XPS range.
Hope that was of some help :S